Patent GB-489458-A (GB)
Title: Improvements in the production of azo-dyestuffs
IPC: C09B29/20
Filed: 1937-08-03
Abstract: Azo dyes; azo dyes, forming upon the material; regenerated celluloses, dyeing.-Insoluble azo compound of an aminoxanthone, which may be substituted by a non-solubilizing group, in substance or on the fibre, with an arylacylacetic acid.  The products can be used for colouring lacquers, varnishes, organic solvents, plastic materials and rubber.  The formation of the dyestuffs on the fibre may be applied to the dyeing of cotton, viscose or other natural or artificial fibres, with or without the intermediate formation of nitrosamines, diazoamino compounds, diazo sulphonates or Schiff's bases.  Examples describe the production, on cotton yarn, of the following dyestuffs: (1) 2-aminoxanthone --> 2 : 3-hydroxynaphthoic acid b -naphthylamide; (2) 4 - aminoxanthone --> 2 : 3-hydroxynaphthoic and anilide; (3) 2-chloro-4-aminoxanthone --> 2 : 3-hydroxynaphthoic acid p-anisidide; (4) 2-amino-3-phenoxyxanthone --> 2 : 3-hydroxynaphthoic acid p-chloro-o-anisidide; (5) 2 - chloro - 4 - aminoxanthone --> 2 : 3-hydroxynaphthoic acid a -naphthylamide. A table gives the properties of further dyestuffs, the following additional coupling components being specified: the m-nitranilide, 5-chloro-2-toluidide, o-toluidide, o-anisidide and 2 : 4-dimethoxy - 5 - chloroanilide of 2 : 3-hydroxynaphthoic acid, and diacetoacetyl-o-toluidine.  Specification 210,217, [Class 2 (iii)], is referred to.  Aminoxanthones.-3 - Aminoxanthone and its substitution products are obtainable by condensing 4 - nitro - 2 - chlorobenzoic acid with phenol, cresols, chlorphenols or analogous compounds, ring-closing the resulting nitrophenylsalicylic acids by heating with sulphuric acid, and reducing the nitro group by means of stannous chloride.  2-Aminoxanthones may be similarly obtained from 4-nitrodiphenyl ether-2-carboxylic acids.  4-Aminoxanthone and its substitution products are obtainable by condensing o-nitrochlorobenzene or 1-nitro-2 : 5-dichlorobenzene with o-cresol or its substitution products, reducing, acetylating, oxidizing the methyl group with potassium permanganate, ring-closing with concentrated sulphuric acid, and diluting and heating to saponify the acetylamino group; alternatively 2 : 5-dichloro-3-nitrobenzoic acid is condensed with phenol or its substitution products, such as cresols or monoalkyl ethers of hydroquinone or resorcinol, and the products are reduced and then ring-closed.  Phenoxylated aminoxanthones are obtainable by condensing phenol or its substitution products with nitropolyhalogen derivatives of benzoic acid having one halogen atom in p- and another in o-position to the nitro group, reducing and ring-closing.  In examples: (1) potassium phenolate is heated with 6-chloro-3-nitrobenzoic acid and the product is heated with strong sulphuric acid and then reduced with iron filings and acetic acid, yielding 2-aminoxanthone; (2) o-chloronitrobenzene is condensed with o-cresol and the product is reduced, acetylated, oxidized with boiling aqueous potassium permanganate and heated with concentrated sulphuric acid, after which the mixture is diluted with water and further heated to produce 4-aminoxanthone; (3) 2-methyl-21-acetylamino-41 - chloro - 1 : 11 diphenyl ether is boiled with potassium permanganate solution, the product is heated with concentrated sulphuric acid, the mixture is diluted with water and heating continued, producing 2 - chloro - 4 - aminoxanthone; (4) potassium phenolate in excess is heated with 5-nitro-2 : 4-dichlorobenzoic acid, the product is heated with iron and glacial acetic acid, and the resulting 5-amino-2 : 4-diphenoxybenzoic acid is heated with somewhat diluted sulphuric acid to yield 2-amino-3-phenoxyxanthone; the product may be diazotized and the diazo compound converted into a double salt with zinc chloride, which may be dried and mixed with aluminium sulphate or dehydrated alum; (5) potassium phenolate is heated with 2 : 5-dichloro - 3 - nitrobenzoic acid, the resulting 2-nitro-4-chloro-6-carboxyl-1 : 11-diphenyl ether is reduced and the product is heated with 85 per cent sulphuric acid to produce 4-amino-2-chloroxanthone.  The Specification as open to inspection under Sect. 91 comprises the use of coupling components of a substantive character in general.  It also contains an additional example in which potassium o-cresolate is heated with p-chloro-m-nitrobenzoic acid, the product is reduced with iron and acetic acid, the resulting amine acetylated with acetic anhydride, and the product oxidized with a solution of potassium permanganate and magnesium sulphate, ring-closed and saponified by heating first with concentrated and then with dilute sulphuric acid, and the resulting 4-aminoxanthone-2-carboxylic acid is esterified by means of ethyl alcohol in the presence of hydrogen chloride.  The product is diazotized and is coupled on the fibre with b  - hydroxynaphthoic acid arylides, e.g. the b -naphthylamide, o- or p-anisidide, p p-chloro-o-anisidide or o-toluidide.  This subject-matter does not appear in the Specification as accepted.ALSO:Rubber is coloured by means of insoluble azo dyestuffs obtained by coupling a diazotized aminoxanthone with an arylamide of an o-hydroxycarboxylic acid or of an acylacetic acid.  Specification 210,317, [Class 51 (i)], is referred to.